Fair Value Measurements - Fair Values of Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Financial assets:
Securities available-for-sale	$ 128,982	$ 97,566
Securities held-to-maturity	0	20,154
Carrying Value
Financial assets:
Interest-bearing deposits in other financial institutions	243,810	128,420
Securities available-for-sale	128,982	97,566
Securities held-to-maturity		20,154
Loans held-for-sale	30,878	1,975
Net loans held-for-investment	1,554,258	1,436,451
FHLB and other restricted stock	8,447	8,345
Accrued interest receivable	11,246	5,136
Financial liabilities:
Deposits	1,647,107	1,479,307
FHLB advances	130,000	20,000
Accrued interest payable	2,626	6,004
Fair Value
Financial assets:
Interest-bearing deposits in other financial institutions	243,810	128,420
Securities available-for-sale	128,982	97,566
Securities held-to-maturity		20,480
Loans held-for-sale	33,770	2,102
Net loans held-for-investment	1,568,235	1,449,383
Accrued interest receivable	11,246	5,136
Financial liabilities:
Deposits	1,653,614	1,468,540
FHLB advances	130,406	20,092
Accrued interest payable	2,626	6,004
Fair Value | Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial assets:
Interest-bearing deposits in other financial institutions	243,810	128,420
Securities available-for-sale	0	0
Securities held-to-maturity		0
Loans held-for-sale	0	0
Net loans held-for-investment	0	0
Accrued interest receivable	4	78
Financial liabilities:
Deposits	0	0
FHLB advances	0	0
Accrued interest payable	0	0
Fair Value | Significant Other Observable Inputs (Level 2)
Financial assets:
Interest-bearing deposits in other financial institutions	0	0
Securities available-for-sale	128,982	97,566
Securities held-to-maturity		20,480
Loans held-for-sale	33,770	2,102
Net loans held-for-investment	0	0
Accrued interest receivable	314	375
Financial liabilities:
Deposits	0	0
FHLB advances	130,406	20,092
Accrued interest payable	2	1
Fair Value | Significant Unobservable Inputs (Level 3)
Financial assets:
Interest-bearing deposits in other financial institutions	0	0
Securities available-for-sale	0	0
Securities held-to-maturity		0
Loans held-for-sale	0	0
Net loans held-for-investment	1,568,235	1,449,383
Accrued interest receivable	10,928	4,683
Financial liabilities:
Deposits	1,653,614	1,468,540
FHLB advances	0	0
Accrued interest payable	$ 2,624	$ 6,003